Hope you're bouncing back OK after the meltdown.
I always hated those things in any of the jobs I ever had. It's like all of the pressure to "pass" and over-stimulation that you would normally have to tolerate at a social gathering, but with the added pressure that there are people there with incredible power over your life, and you can't avoid seeing everyone again while they pick over everything that happened around the water-cooler. I also can't stand that fake drunken friendliness from people to whom you're just a 'cog in the machine' at any other time.
And of course, there's always that sneaking anxiety that if you don't go, it's a black mark against your name for "not having the team spirit."
I have as much of a circle of friends as I can cope with in my personal life, I don't want the added complication of personal relationships at work; I just want to get my job done and get paid. I can barely cope with a job as it is, but at the very least it has to exist in a very separate "compartment" to the rest of my life so that I have a chance to switch it off when I get home.
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When you are fighting an invisible monster, first throw a bucket of paint over it.